When parts of the frame or sash are so badly deteriorated that
they cannot be stabilized there are methods which permit the
retention of some of the existing or original fabric. These
methods involve replacing the deteriorated parts with new matching
pieces, or splicing new wood into existing members.

The techniques require more skill and are more expensive than
any of the previously discussed alternatives. It is necessary
to remove the sash and/or the affected parts of the frame and
have a carpenter or woodworking mill reproduce the damaged or
missing parts. Most millwork firms can duplicate parts, such
as muntins, bottom rails, or sills, which can then be incorporated
into the existing window, but it may be necessary to shop around
because there are several factors controlling the practicality
of this approach.

Some woodworking mills do not like to repair old sash because
nails or other foreign objects in the sash can damage expensive
knives (which cost far more than their profits on small repair
jobs); others do not have cutting knives to duplicate muntin
profiles. Some firms prefer to concentrate on larger jobs with
more profit potential, and some may not have a craftsman who
can duplicate the parts. A little searching should locate a
firm which will do the job, and at a reasonable price. If such
a firm does not exist locally, there are firms which undertake
this kind of repair and ship nationwide.

It is possible, however, for the advanced do-it-yourselfer
or craftsman with a table saw to duplicate moulding profiles
using techniques discussed by Gordie Whittington in "Simplified
Methods for Reproducing Wood Mouldings," Bulletin
of the Association for Preservation Technology, Vol. III, No.
4, 1971, or illustrated more recently in The Old House,
Time-Life Books, Alexandria, Virginia, 1979.

The repairs discussed in this section involve window frames
which may be in very deteriorated condition, possibly requiring
removal; therefore, caution is in order. The actual construction
of wooden window frames and sash is not complicated. Pegged
mortise and tenon units can be disassembled easily, if the units
are out of the building. The installation or connection of some
frames to the surrounding structure, especially masonry walls,
can complicate the work immeasurably, and may even require dismantling
of the wall. It may be useful, therefore, to take the following
approach to frame repair:

conduct regular maintenance of sound frames to achieve
the longest life possible,

make necessary repairs in place, wherever possible, using
stabilization and splicing techniques, and

if removal is necessary, thoroughly investigate the structural
detailing and seek appropriate professional consultation.

Another alternative may be considered if parts replacement
is required, and that is sash replacement. If extensive replacement
of parts is necessary and the job becomes prohibitively expensive
it may be more practical to purchase new sash which can be installed
into the existing frames. Such sash are available as exact custom
reproductions, reasonable facsimiles (custom windows with similar
profiles), and contemporary wooden sash which are similar in
appearance. There are companies which still manufacture high
quality wooden sash which would duplicate most historic sash.
A few calls to local building suppliers may provide a source
of appropriate replacement sash, but if not, check with local
historical associations, the state historic preservation office,
or preservation related magazines and supply catalogs for information.

If a rehabilitation project has a large number of windows
such as a commercial building or an industrial complex, there
may be less of a problem arriving at a solution. Once the evaluation
of the windows is completed and the scope of the work is known,
there may be a potential economy of scale. Woodworking mills
may be interested in the work from a large project; new sash
in volume may be considerably less expensive per unit; crews
can be assembled and trained on site to perform all of the window
repairs; and a few extensive repairs can be absorbed (without
undue burden) into the total budget for a large number of sound
windows. While it may be expensive for the average historic
home owner to pay seventy dollars or more for a mill to grind
a custom knife to duplicate four or five bad muntins, that cost
becomes negligible on large commercial projects which may have
several hundred windows.

Most windows should not require the extensive repairs discussed
in this section. The ones which do are usually in buildings
which have been abandoned for long periods or have totally lacked
maintenance for years. It is necessary to thoroughly investigate
the alternatives for windows which do require extensive repairs
to arrive at a solution which retains historic significance
and is also economically feasible. Even for projects requiring
repairs identified in this section, if the percentage of parts
replacement per window is low, or the number of windows requiring
repair is small, repair can still be a cost effective solution.